HexKeys is basically a geeky virtual simulation of the Axis 64 Midi Controller and it's not just for ProTools. Phone/Tablet MIDI controller apps can be used to manipulate any software that has MIDI input. Most people use Ableton Live for this kind of experimentation these days.
Manufacturing hardware that uses anything but the traditional horizontal row of black and white keys is risky because there just isn't a very big market for it. Making an app that does the same thing is much less risky. The keyboard that Grant Kot uses in his Grantophone Win8 app is more like a modified version of another specialized controller called the Kaken Continuum which is also expensive but could be simulated with a tablet app for just a few dollars.
That's what's so great about multi-touch wireless MIDI controller apps. They're endlessly configurable unlike real hardware and they're inexpensive.
Now, if I only owned a phone I could test out Meedy Wifi
I just looked at HexKeys link. What is the use? Just a simple music controller. Is this for a game? I am curious how this is intended to be used. It's a phone-based or device-based keyboard that sends MIDI signals over one's wifi lan... to ProTools? Seems a bit cramped for a musician... Hmm.